Java tutorial
/* * Copyright 2014 Google Inc. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package oly.netpowerctrl.ui.widgets; import android.content.Context; import android.database.DataSetObserver; import android.graphics.Typeface; import android.support.v4.view.PagerAdapter; import android.util.AttributeSet; import android.util.SparseArray; import android.util.TypedValue; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; import android.widget.TextView; /** * To be used with ViewPager to provide a tab indicator component which give constant feedback as to * the user's scroll progress. * <p/> * To use the component, simply add it to your view hierarchy. Then in your * {@link android.app.Activity} or {@link android.support.v4.app.Fragment} call * {@link #setViewPagerAdapter(android.support.v4.view.PagerAdapter)} providing it the ViewPager this layout is being used for. * <p/> * The colors can be customized in two ways. The first and simplest is to provide an array of colors * via {@link #setSelectedIndicatorColors(int...)}. The * alternative is via the {@link TabColorizer} interface which provides you complete control over * which color is used for any individual position. * <p/> * The views used as tabs can be customized by calling {@link #setCustomTabView(int, int)}, * providing the layout ID of your custom layout. */ public class SlidingTabLayout extends HorizontalScrollView { private static final int TITLE_OFFSET_DIPS = 24; private static final int TAB_VIEW_PADDING_DIPS = 16; private static final int TAB_VIEW_TEXT_SIZE_SP = 12; private final SlidingTabStrip mTabStrip; private int mTitleOffset; private int mTabViewLayoutId; private int mTabViewTextViewId; private boolean mDistributeEvenly; private int currentPosition = 0; private PagerAdapter mPageAdapter; private SparseArray<String> mContentDescriptions = new SparseArray<>(); private DataSetObserver dataSetObserver = new DataSetObserver() { @Override public void onInvalidated() { mTabStrip.removeAllViews(); populateTabStrip(); } @Override public void onChanged() { mTabStrip.removeAllViews(); populateTabStrip(); } }; private onTabClickedListener tabClickedListener; public SlidingTabLayout(Context context) { this(context, null); } public SlidingTabLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // Disable the Scroll Bar setHorizontalScrollBarEnabled(false); // Make sure that the Tab Strips fills this View setFillViewport(true); mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density); mTabStrip = new SlidingTabStrip(context); addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } /** * Set the custom {@link TabColorizer} to be used. * <p/> * If you only require simple custmisation then you can use * {@link #setSelectedIndicatorColors(int...)} to achieve * similar effects. */ public void setCustomTabColorizer(TabColorizer tabColorizer) { mTabStrip.setCustomTabColorizer(tabColorizer); } public void setDistributeEvenly(boolean distributeEvenly) { mDistributeEvenly = distributeEvenly; } public int getCurrentPosition() { return currentPosition; } public int getCount() { return mPageAdapter.getCount(); } /** * Sets the colors to be used for indicating the selected tab. These colors are treated as a * circular array. Providing one color will mean that all tabs are indicated with the same color. */ public void setSelectedIndicatorColors(int... colors) { mTabStrip.setSelectedIndicatorColors(colors); } /** * Set the custom layout to be inflated for the tab views. * * @param layoutResId Layout id to be inflated * @param textViewId id of the {@link android.widget.TextView} in the inflated view */ public void setCustomTabView(int layoutResId, int textViewId) { mTabViewLayoutId = layoutResId; mTabViewTextViewId = textViewId; } /** * Sets the associated view pager. Note that the assumption here is that the pager content * (number of tabs and tab titles) does not change after this call has been made. */ public void setViewPagerAdapter(PagerAdapter viewPager) { if (mPageAdapter != null) mPageAdapter.unregisterDataSetObserver(dataSetObserver); mPageAdapter = viewPager; mPageAdapter.registerDataSetObserver(dataSetObserver); mTabStrip.removeAllViews(); if (mPageAdapter != null) { populateTabStrip(); } } /** * Create a default view to be used for tabs. This is called if a custom tab view is not set via * {@link #setCustomTabView(int, int)}. */ protected TextView createDefaultTabView(Context context) { TextView textView = new TextView(context); textView.setGravity(Gravity.CENTER); textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP); textView.setTypeface(Typeface.DEFAULT_BOLD); textView.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)); TypedValue outValue = new TypedValue(); getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground, outValue, true); textView.setBackgroundResource(outValue.resourceId); textView.setAllCaps(true); int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density); textView.setPadding(padding, padding, padding, padding); return textView; } private void populateTabStrip() { final TabClickListener tabClickListener = new TabClickListener(); for (int i = 0; i < mPageAdapter.getCount(); i++) { View tabView = null; TextView tabTitleView = null; if (mTabViewLayoutId != 0) { // If there is a custom tab view layout id set, try and inflate it tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip, false); tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId); } if (tabView == null) { tabView = createDefaultTabView(getContext()); } if (tabTitleView == null && TextView.class.isInstance(tabView)) { tabTitleView = (TextView) tabView; } if (mDistributeEvenly) { LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) tabView.getLayoutParams(); lp.width = 0; lp.weight = 1; } tabTitleView.setText(mPageAdapter.getPageTitle(i)); tabView.setOnClickListener(tabClickListener); tabView.setOnLongClickListener(tabClickListener); String desc = mContentDescriptions.get(i, null); if (desc != null) { tabView.setContentDescription(desc); } mTabStrip.addView(tabView); if (i == currentPosition) { tabView.setSelected(true); } } } public void setContentDescription(int i, String desc) { mContentDescriptions.put(i, desc); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); if (mPageAdapter != null) { scrollToTab(currentPosition, 0); } } private void scrollToTab(int tabIndex, int positionOffset) { final int tabStripChildCount = mTabStrip.getChildCount(); if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) { return; } View selectedChild = mTabStrip.getChildAt(tabIndex); if (selectedChild != null) { int targetScrollX = selectedChild.getLeft() + positionOffset; if (tabIndex > 0 || positionOffset > 0) { // If we're not at the first child and are mid-scroll, make sure we obey the offset targetScrollX -= mTitleOffset; } scrollTo(targetScrollX, 0); } } public void onPageResetScrolled() { mTabStrip.onViewPagerPageChanged(currentPosition, 0f); } public void onPageScrolled(boolean fromRight, float positionOffset) { int position = currentPosition; if (fromRight) { --position; if (position < 0) return; positionOffset = 1f - positionOffset; } // Log.w("onPageScrolled", String.valueOf(position) + " "+String.valueOf(positionOffset)); mTabStrip.onViewPagerPageChanged(position, positionOffset); View selectedTitle = mTabStrip.getChildAt(position); int extraOffset = (selectedTitle != null) ? (int) (positionOffset * selectedTitle.getWidth()) : 0; scrollToTab(position, extraOffset); } public void changeToPosition(int position) { currentPosition = position; mTabStrip.onViewPagerPageChanged(position, 0f); scrollToTab(position, 0); for (int i = 0; i < mTabStrip.getChildCount(); i++) { mTabStrip.getChildAt(i).setSelected(position == i); } } public void setTabClickedListener(onTabClickedListener tabClickedListener) { this.tabClickedListener = tabClickedListener; } /** * Allows complete control over the colors drawn in the tab layout. Set with * {@link #setCustomTabColorizer(TabColorizer)}. */ public interface TabColorizer { /** * @return return the color of the indicator used when {@code position} is selected. */ int getIndicatorColor(int position); } public interface onTabClickedListener { void onTabClicked(int position); void onTabLongClicked(View view, int position); } private class TabClickListener implements OnClickListener, OnLongClickListener { @Override public void onClick(View view) { for (int i = 0; i < mTabStrip.getChildCount(); i++) { if (view == mTabStrip.getChildAt(i)) { currentPosition = i; if (tabClickedListener != null) tabClickedListener.onTabClicked(currentPosition); return; } } } @Override public boolean onLongClick(View view) { for (int i = 0; i < mTabStrip.getChildCount(); i++) { if (view == mTabStrip.getChildAt(i)) { currentPosition = i; if (tabClickedListener != null) tabClickedListener.onTabLongClicked(view, currentPosition); return true; } } return false; } } }